Prolonged application of pressure in transluminal coronary angioplasty.

We investigated the morphologic structure and fluid content of atherosclerotic specimens of fresh human postmortem artery segments before and after application of a pressure of 5 atmospheres simulated by a weight of 5 kg per 1 cm2. After applying pressure in nonorganized atheromata, we noticed a marked reduction in thickness while in fibrotic atheromata we observed only smaller differences in thickness. Reduction in fluid content was significantly more pronounced in nonorganized atheromatous tissue. Reduction in thickness was closely related to reduction in weight (i e, fluid content). The time of pressure application necessary to achieve the optimal result averaged 60 sec. The conclusions drawn from these experiments were incorporated into clinical application of coronary angioplasty. Prolonged balloon inflation was applied to the last 400 out of a total of 600 coronary angioplasty procedures, performed between October 1977 and October 1983. Stenoses not sufficiently responsive to balloon inflation periods of 5-10 sec were exposed to periods of 60 sec (30-120 sec). The number of "non dilatable" stenoses was 15% with the standard short pressure procedure, but only 5% with the prolonged pressure application. No serious complications related to prolonged pressure application were observed. Thus, from experimental data and clinical experience the application of longer pressure periods appears justified and beneficial.